The present invention relates to a method for interpolating a video signal.
In the plasma display panel (PDP), liquid crystal display panel (LCD), electroluminescence display device (EL), and others, the number of horizontal pixels at every scanning line, the number of scanning lines, and scanning frequency are set at predetermined values.
Therefore, in order to input a video signal of the NTSC system for displaying the video signal in a display device in which the number of horizontal pixels, the number of scanning lines and scanning frequency are set for the HDTV, it is necessary to covert the video signal so as to increase the number of horizontal pixels at every scanning line and the number of scanning lines.
FIG. 3 shows an example of a conventional method for producing interpolation pixels. At shown in the drawing, an interpolation component at the left side of each of pixels a to f is designated by a triangle l, and an interpolation component at the right side is designated by a square r. The value of each interpolation component is set to ½ of the pixel value. The interpolation component r at the right side of the present pixel at the left side of an assumption interpolation pixel x and the interpolation component l at the left side of the present pixel at the right side of the interpolation pixel x are added together, and the average is calculated. In other words, the average of pixel data of present pixels at both sides of the interpolation pixel x on the same scanning line is obtained, and the average is inserted between present pixels as a pixel data of the interpolation pixel.
However, in the average interpolation method peak values in the video signal are lost at the sampling and conversion to a digital signal. It is difficult to reproduce the lost peak value. Therefore, there is a problem that the picture is inferior in sharpness and picture quality.